The invention relates to an alarm clock according to the generic clause of patent claim 1.
In CH patent specification No. 638,367 a wrist watch having settable, time-dependent signalling is described. This watch has an alarm-setting wheel which is adjustable from the outside by means of a button and mountingly disposed coaxial to the hour wheel on the hour-wheel pipe. The alarm-setting wheel is part of a circuit comprising an electronic control circuit and a battery electrically connected to the hour wheel. The circuit serves to control an alarm signal device and is closed by means of a contact spring resiliently secured to one side of the hour wheel, which contact spring meets a contact stud that passes through the electrically insulating minute-setting wheel and is electrically connected to a circular conductor path on the alarm-setting wheel. The contact spring glides over the insulating surface of the alarm-setting wheel until it touches the contact stud; in this connection there is an enormous risk of contamination of the contact surface, and contact-making is ill-defined in the beginning stage of the contact between the contact spring and the stud. Moreover, it is necessary that the contact spring be precisely adjusted at the time of assembly.